In its decision, the FCC said any devices capable of receiving digital television signals must include support for a "broadcast flag," or digital marker, within a broadcast that would prevent copies from being made without some kind of copy protection being added. The consumer groups say the FCC has overstepped its mandate by getting into the copyright protection arena.

"We're saying the FCC action went beyond its jurisdiction," said Fred von Lohmann, an attorney with the Electronic Frontier Foundation. "We don't think there was enough basis to support the ruling."

The broadcast flag controversy, while far less visible than the debates over peer-to-peer networks, is one of the key issues in the passage of traditional entertainment companies into the digital world.

The Motion Picture Association of America, along with television companies, have argued that moving their content to digital television would be impossible, if people could easily make perfect digital copies of movies and other programming, and swap them online.

The broadcast flag is viewed by regulators as a way to stop online distribution of over-the-air transmissions. Cable TV and satellite customers already receive encrypted signals that are difficult to copy.

Under the rules passed last November, support for the flag must be built into all digital TV devices by July 2005. That wouldn't stop all copies from being made. Analog copies, as to a VCR, would not be blocked, and digital copies made to "approved" devices that include some level of copy protection would also be allowed. The aim is not to stop personal copying but to prevent those copies from finding their way into mass distribution, regulators said.

The consumer and civil liberties groups say this would infringe protected use of content and would disable features people have come to expect in their own property, however.

The court case may be put temporarily on hold while the FCC itself hears other objections to the ruling, a typical process for controversial issues, an FCC representative said.